Inter-modulation distrotion reduction in multi-mode wireless communication terminal

ABSTRACT

A multimode wireless communication terminal that communicates using a first radio access technology (RAT) and a second RAT determines whether the first and second RATs are in an active state, and modifies a maximum transmit power limit of the first RAT based on a voice codec rate of a voice transmission on the second RAT when the first RAT and the second RAT are in the active state concurrently, wherein the second RAT is conducting the voice transmission in the active state. In an alternative embodiment, the limit is modified based on a transmit power status of the second RAT or on a transmission type of the first RAT.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications and,more particularly, to the avoidance or reduction of inter-modulation(IM) distortion in multimode wireless communication terminals andcorresponding methods.

BACKGROUND

The introduction of new wireless radio access technologies usuallyoccurs in stages due to financial and logistical considerations. Forexample, it is common for evolved radio access technology (RAT)infrastructure to be implemented initially in areas with higherpopulation density amidst existing radio access technologyinfrastructure. Such implementations often require multi-mode userterminals supporting the different radio access technologies. Theemerging 3GPP LTE radio access technology will be likely be implementedusing multimode user equipment (UE) that supports OFDM and CDMAtechnologies operating simultaneously in neighboring frequency bands. Inthe United States, for example, simultaneous activation (i.e., uplinktransmission) of a CDMA RAT operating at 850 MHz and an OFDM RAToperating at 700 MHz may result in desense of one or the other radioaccess technologies.

Emerging broadband wireless networks such as 3GPP LTE must solve theproblems of minimizing the power amplifier (PA) power consumption (orpeak and/or mean current drain), cost and the complexity required todeliver a specified conducted power level in the context of new modes ofsystem operation. For example, PA performance must be optimized in thepresence of numerous different frequency or spatially adjacent radioaccess technologies, including GSM, UMTS, WCDMA, unlicensed transmitterand receivers, among other radio access technologies.

Exemplary cellular communication networks include 2.5 Generation 3GPPGSM networks, 3rd Generation 3GPP WCDMA networks, and 3GPP2 CDMAcommunication networks, among other existing and future generationcellular communication networks. Future generation networks include thedeveloping Universal Mobile Telecommunications System (UMTS) networks,Evolved Universal Terrestrial Radio Access (E-UTRA) networks. Thenetwork may also be of a type that implements frequency-domain orientedmulti-carrier transmission techniques, such as Frequency DivisionMultiple Access (OFDM), DFT-Spread-OFDM (DFT-SOFDM), InterleavedFrequency Division Multiple Access (IFDMA), etc., which are of interestfor future systems. Single-carrier based approaches with orthogonalfrequency division (SC-FDMA), particularly IFDMA and itsfrequency-domain related variant known as DFT-SOFDM, are attractive inthat they optimize performance when assessed using contemporary waveformquality metrics, which may include peak-to-average power ratio (PAPR) orthe so-called cubic metric (CM).

In OFDM networks, both Time Division Multiplexing (TDM) and FrequencyDivision Multiplexing (FDM) are employed to map channel-coded,interleaved and data-modulated information onto OFDM time/frequencysymbols. The OFDM symbols can be organized into a number of resourceblocks consisting of M consecutive sub-carriers for a number Nconsecutive OFDM symbols where each symbol may also include a guardinterval or cyclic prefix (CP). An OFDM air interface is typicallydesigned to support carriers of different bandwidths, e.g., 5 MHz, 10MHz, etc. The resource block size in the frequency dimension and thenumber of available resource blocks are generally dependent on thebandwidth of the system.

User equipment operating in a cellular network operate in a number of‘call states’ or ‘protocol states’ generally conditioned on actionsapplicable in each state. For example, in a mode typically referred toas an ‘idle’ mode, a UE may roam throughout a network withoutnecessarily initiating or soliciting uplink or downlink traffic, except,e.g., to periodically perform a location update to permit efficientnetwork paging. In another such protocol state, the UE may be capable ofinitiating network access via a specified shared channel, such as arandom access channel (RACH). A UE's ability or need to access physicallayer resources may be conditioned on the protocol state. In somenetworks, for example, the UE may be permitted access to a sharedcontrol channel only under certain protocol-related conditions, e.g.,during initial network entry. Alternatively, a UE may have a requirementto communicate time-critical traffic, such as a handover request oracknowledgement message, with higher reliability.

The various aspects, features and advantages of the invention willbecome more fully apparent to those having ordinary skill in the artupon careful consideration of the following Detailed Description thereofwith the accompanying drawings described below. The drawings may havebeen simplified for clarity and are not necessarily drawn to scale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to one aspect of thedisclosure.

FIG. 2 illustrates a schematic block diagram of a multimode wirelesscommunication terminal.

FIG. 3 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to another aspect ofthe disclosure.

FIG. 4 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to another aspect ofthe disclosure.

FIG. 5 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to another aspect ofthe disclosure.

FIG. 6 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to yet anotheraspect of the disclosure.

FIG. 7 illustrates a flow diagram of a process implemented in amultimode wireless communication terminal according to still anotheraspect of the disclosure.

DETAILED DESCRIPTION

In wireless communication system comprising different radio accesstechnologies, each RAT generally includes corresponding radio accessnetworks and in some implementations corresponding core networks. Anaccess network typically includes one or more base stations that serveuser terminals in corresponding cellular areas or regions, wherein theone or more access network communicably coupled to a controller. Thecore network generally provides switching and routing functionality foruser traffic. In some systems, multiple access networks may share acommon core network and in other systems multiple core networks mayshare a common access network. Other networks could be configureddifferently. In one example described below, one RAT is OFDM based, forexample, 3GPP LTE, and the other RAT is CDMA based, for example 1xRTT(CDMA 1x). More generally, however, the different radio accesstechnologies may be any technologies that operate in or on neighboringor overlapping frequencies that result in desense of one or the otherradio access technologies. For example, operation of a transmitter onone RAT may result in desense of a receiver of another RAT.

Generally, a wireless communication network infrastructure schedulingentity located allocates or assigns radio resources to schedulablewireless communication entities, e.g., mobile terminals, in the wirelesscommunication network. In FIG. 1, each base stations includes ascheduler for scheduling and allocating radio resources to mobileterminals in corresponding cellular areas. In multiple access schemessuch as those based on OFDM methods, multi-carrier access ormulti-channel CDMA wireless communication protocols including, forexample, IEEE-802.16e-2005, multi-carrier HRPD-A in 3GPP2, and the LongTerm Evolution (LTE) of UTRA/UTRAN Study Item in 3GPP (also known asevolved UTRA/UTRAN (EUTRA/EUTRAN)), scheduling may be performed in thetime and frequency dimensions using a Frequency Selective (FS)scheduler. To enable FS scheduling by the scheduler, in someembodiments, each mobile terminal provides a per frequency band channelquality indicator (CQI) to the scheduler.

In OFDM systems, a resource allocation is a frequency and timeallocation that maps information for a particular UE to resource blocksas determined by the scheduler. This allocation depends, for example, onthe frequency-selective channel-quality indication (CQI) reported by theUE to the scheduler. The channel-coding rate and the modulation scheme,which may be different for different resource blocks, are alsodetermined by the scheduler and may also depend on the reported CQI. AUE may not be assigned every sub-carrier in a resource block. It couldbe assigned every Qth sub-carrier of a resource block, for example, toimprove frequency diversity. Thus a resource assignment can be aresource block or a fraction thereof. More generally, a resourceassignment is a fraction of multiple resource blocks. Multiplexing oflower-layer control signaling may be based on time, frequency and/orcode multiplexing.

The radio resource allocated to a schedulable wireless communicationentity is based on an interference impact of the schedulable wirelesscommunication entity operating on the radio resource allocated. Theinterference impact may be based on any one or more of the followingfactors: a transmission waveform type of the schedulable wirelesscommunication entity; a maximum allowed and current power level of theschedulable wireless communication entity; bandwidth assignable to theschedulable wireless communication entity; location of the assignablebandwidth in a carrier band; radio frequency distance (path loss)relative to another wireless communications entity; variation in themaximum transmit power of the schedulable wireless communication entityfor the assigned bandwidth; separation of assigned band relative to theother wireless communication entity; reception bandwidth of the victimentity, minimum SNR required for operation of the victim entity; andreception multiple access processing (e.g., CDMA, OFDM, or TDMA), amongother factors. The variation in the maximum transmit power includesde-rating or re-rating the maximum transmit power of the wirelesscommunication entity as discussed below.

For a given carrier band and band separation, transmissions with largeroccupied bandwidth (OBW) create more out of band emissions resulting ina larger adjacent or neighbor channel leakage ratio (ACLR) thantransmissions with smaller OBW. To avoid the relative increase in ACLR,it is generally necessary to reduce or de-rate transmission powercreated by the interfering entity. This can be generally achieved byapplying a Maximum Power Reduction (MPR) and an optional additionalMaximum Power Reduction (A-MPR) to the maximum power of the mobileterminal. If P_(MAX) is the maximum power at which the mobile terminalis capable of transmitting, applying an MPR and A-MPR will reduce themaximum power at which the terminal can transmit to P_(MAX)-MPR-AMPR.

It is known for the scheduler to allocate the radio resource based onthe interference impact by assigning bandwidth based on power headroomof the schedulable wireless communication entity. Particularly, thescheduler can find a bandwidth size that reduces required MPR and A-MPRenough such that operational maximum power (P_(MAX)-MPR-AMPR) does notlimit current power of the schedulable wireless communication entity.

A scheduler may also control leakage into adjacent and non-contiguousadjacent bands by scheduling mobile terminals that are “close” to theserving cell in terms of path loss with bandwidth allocations thatoccupy the entire carrier band or a bandwidth allocation that includesresource blocks (RBs) that are at the edge of the carrier band (e.g., 5MHz UTRA or LTE carrier) since due to power control it is very unlikelythat such a terminal will be operating at or near to P_(MAX) andtherefore unlikely that its current power level would be limited by theoperational maximum power (P_(MAX)-MPR-AMPR). A scheduler may scheduleterminals that have little or no power margin with bandwidth allocationsthat exclude resource blocks at the carrier band edge reducing thelikelihood of the terminal being power limited by the operationalmaximum power. In systems having different networks that are runindependently, such as CDMA 1x and LTE networks, the schedulersupporting one radio access technology in one network operatesindependently of the scheduler supporting a different radio accesstechnology in the other network. A multimode UE may then need totransmit over the two radio access technologies at the same time.

The power radiated into an adjacent frequency band by a UE, and thedistortion offered by a UE to a another UE is governed by several designcriteria related to the implementation of mobile terminal transmitters,including oscillator phase noise, digital-analog converter (DAC) noise,power amplifier (PA) linearity (in turn controlled by power amplifiermode, cost, power consumption etc.), among others.

Generally, however, and in common with most non-linear transformationsexpandable in terms a polynomial power series, UE power amplifiers giverise to undesired adjacent band interference in broad proportion, for agiven PA design, to the mean power offered to the PA input. As aconsequence of 3^(rd) or 5^(th) order polynomial terms, the frequency atwhich interference occurs is at 3 or 5 times the frequency of the inputsignal components, or harmonics thereof. Also, the power of suchout-of-band components generally increases at 3 or 5 times the rate ofincrease of the input power level.

Accordingly, mobile terminals may control their out of band emissionlevels by limiting the power to the PA. Given a specific rated maximumoutput (or input) power level designed to achieve a given level ofinterference into an adjacent frequency band, or level of in-banddistortion, a mobile terminal may elect to adjust, for example, reduceits input, power level in order to reduce such unwanted effects. Themobile terminal may also keep its power at a given level, but adjust itsoperating point (load, bias, supply, etc.) to effect adjustment of theemission levels. As described elsewhere herein, a decision to increaseor decrease the input or output PA power may be subject to othercriteria, including waveform bandwidth, location in a frequency band,waveform quality metric, among other considerations.

In a dual RAT UE transmitting on both RATs simultaneously, the UE mightneed to apply a large maximum power reduction at all times. For the casewhere a CDMA 1x transmitter is interfering with an LTE receiver, such areduction may be required on an LTE RAT to avoid LTE receiver desense inthe event that both RATs (e.g., CDMA at 850 MHz band and LTE at 700 MHzband) are active (e.g., simultaneous uplink transmission on both RATs).In FIG. 1, according to one aspect of the disclosure, a multimodewireless communication terminal that communicates using a first radioaccess technology (RAT) and a second RAT determines, at 110, whether thefirst RAT and the second RAT are in an active state. A RAT is in anactive state if the corresponding UE has been assigned a temporaryidentifier for communicating with a network on the RAT or if the UE hasa context in the base station. The context includes the temporaryidentifier of the UE in the base station and information related to thetraffic being supported through the base station such as protocol stackconfiguration, etc.

In FIG. 1, at 120, when both the first RAT and the second RAT are in theactive state at the same time, the wireless communication terminalmodifies a maximum transmit power limit of the first RAT based on avoice codec rate of a voice transmission on the second RAT, wherein thesecond RAT is conducting the voice transmission in the active state. Thewireless communication terminal then transmits at a transmit power levelon the first RAT based on the modified maximum transmit power limit. Forexample, the terminal transmits at the modified transmit power levelwhen the voice transmission is conducted on the second RAT.

FIG. 2 illustrates a multimode terminal or UE 200 comprising a first RATtransceiver 210 and a second RAT transceiver 220 communicably coupled toa controller 230. The transceivers may implement any wirelesscommunication protocols, as discussed above, and may be capable ofconducting circuit or packet switched communications or both. The UE mayalso comprise other elements for performing other functionalitytypically associated with wireless communication terminals, includingbut not limited to user interface elements. These and other elements ofsuch terminals are well known to those of ordinary skill in the art andare not described further herein.

In the multimode terminal of FIG. 2, the controller is configured toperform RAT state determination functionality 232 by implementinginstructions stored in a memory device constituting the terminal. Moreparticularly, the controller determines whether the first and secondRATS are in the active state as defined herein. Alternatively, the RATstate determination functionality may be performed by implementingequivalent hardware circuits or by implementing some other combinationof software controlled hardware elements. The controller is alsoconfigured generally, to perform maximum transmit power modification234. In the embodiment of FIG. 2, the controller modifies the maximumtransmit power of the first RAT based on a voice codec rate of a voicetransmission on the second RAT when the first RAT and the second RAT arein the active state concurrently.

In one implementation, the maximum transmit power limit of the first RATis modified based on the voice codec rate of the second RAT byincreasing the maximum transmit power limit of the first RAT when thesecond RAT conducts the voice transmission using a relatively low voicecodec data rate. In another implementation, the maximum transmit powerlimit of the first RAT is decreased when the second RAT conducts thevoice transmission using a relatively high voice codec data rate.

In another embodiment, the wireless communication terminal modifies amaximum transmit power limit of the second RAT when modifying themaximum transmit power limit of the first RAT, when the first RAT andthe second RAT are in the active state at the same time.

In another embodiment, the wireless communication terminal changes themaximum transmit power limit of the first RAT during a silence period ofthe voice transmission relative to a non-silence period of the voicetransmission, when the first RAT and the second RAT are in the activestate at the same time. In a more particular implementation, the maximumtransmit power limit of the first RAT is increased during the silenceperiod of the voice transmission. In an alternative implementation, theterminal reduces the maximum transmit power limit of the second RATduring the silence period of the voice transmission.

A silence period is characterized by no transmission due to a UE goinginto a quasi-idle state (e.g., a DRX state in LTE), which might occurbetween some packet transmissions, e.g., voice transmissions. A silenceperiod can also reflect voice inactivity that occurs during talk spurtsdue, e.g., to pauses by the speaker or the speaker listening to theother caller. Some codecs (e.g., AMR) characterize this inactivity bysending a Silence Information Descriptor (SID) voice packet withrelatively few bits (e.g., 39 bits including packet overhead) comparedto a normal voice packet corresponding to speech (voice activity) whichwill typically carry 200 hundred bits or more. In other codecs, (likeEVRC), that dynamically switch rates based on voice activity and theamount of speech information contained in the speaker's utterances, amuch lower coding rate (e.g., 1200 bps) is used for the silence orinactivity period compared to the active period (e.g., 9600 bps).

The terminal is typically configured to send reports indicating itsavailable power headroom to assist the scheduler in the base station toallocate resources in an appropriate manner. In order to provide newinformation, distinct from the original intent of the report there maybe new agreements that certain report field values or states orcombinations thereof are to be interpreted differently. Furtherconditions might include UE status or call state or configured modes orpower status or buffer status or currently transmitted sub-frame/frametype (e.g., 8^(th) rate frame versus full rate frame or whether data orcontrol is being transmitted) or even multiple occurrences of a reportor report type in the same transmitted sub-frame or frame.

In FIG. 3, according to another aspect of the disclosure, a multimodewireless communication terminal that communicates using a RAT and thatcommunicates using a second RAT determines, at 310, whether the firstRAT and the second RAT are in an active state, as described herein. InFIG. 3, at 320, when both the first RAT and the second RAT are in theactive state at the same time, the wireless communication terminalmodifies a maximum transmit power limit of the first RAT based on eithera transmit power status of the second RAT or based on a transmissiontype of the first RAT when both the first RAT and the second RAT areconcurrently in the active state.

In FIG. 2, the controller 230 is configured to perform the maximumtransmit power modification according to this embodiment by implementinginstructions stored in memory or using equivalent circuitry. Theterminal may then transmit at a power level on the first RAT based onthe modified maximum transmit power limit when the first RAT and thesecond RAT are in the active state concurrently. In the embodiment, ofFIG. 3, the criteria on which the maximum transmit power is modified isdifferent than the modification criteria of FIG. 1. The controller maygenerally be programmed to modify the maximum transmit power based onany one or more of the criterion used in the embodiments of FIGS. 1 and3, namely, the voice codec rate, or the transmit power status, or thetransmission type, or some combination of these elements.

In one embodiment, the transmission type on the first RAT may be eithera control transmission or a data transmission. The transmission type onthe first RAT may also be either a frequency hopping transmission or anon-frequency hopping transmission. In another embodiment, the terminalincreases the maximum transmit power limit of the first RAT when thetransmission type of the first RAT is a control transmission. In arelated embodiment, the maximum transmit power limit of the first RAT isincreased and the maximum transmit power limit of the second RAT isdecreased when the transmission type of the first RAT is a controltransmission. In one embodiment when the transmission type of the firstRAT is a data transmission, the maximum transmit power limit of thefirst RAT is decreased and a maximum transmit power limit of the secondRAT is increased.

In one embodiment, the transmit power status of the second RAT isselected from a group comprising: a transmit power headroom of thesecond RAT; a transmit power level of the second RAT; and a maximumtransmit power limit of the second RAT. According to this embodiment,the transmit power status of the second RAT could be a transmit powerlevel of the second RAT, or a transmit power headroom of the second RAT,or a maximum transmit power limit of the second RAT.

In one implementation, the modification of the maximum transmit powerlimit of the first RAT occurs over only a single slot of a sub-framewherein only the single slot includes transmissions in frequencyresources that desense the second RAT whereas one or more other slots ofthe sub-frame do not include transmissions in frequency resources thatdesense the second RAT.

In FIG. 4, according to another aspect of the disclosure, a multimodewireless communication terminal that communicates using a first radioaccess technology (RAT) and a second RAT determines, at 410, whether thefirst RAT and the second RAT are in an active state. At 420, when thewireless communication terminal is transmitting on the first RAT and thesecond RAT concurrently, the terminal transmits uplink controlinformation (UCI) on a PUSCH on the first RAT if there is a scheduledPUSCH transmission, wherein the UCI would otherwise be transmitted on aPUCCH when the wireless communication terminal is not transmitting usingthe second RAT while transmitting on the first RAT and there is ascheduled PUSCH on the first RAT.

The PUCCH is used to transmit uplink control information (UCI) to thenetwork. The PUCCH is used to convey CQI information, ACK/NACKinformation, etc. The UCI may piggy back over a PUSCH in case ofsimultaneous PUCCH and PUSCH allocations in the same sub-frame. This isnecessary to preserve the single carrier nature of the uplink waveform.Simultaneous PUCCH and PUSCH transmissions over separate uplinkallocations are generally allowed. In the case of a dual RAT supportingterminal, and the terminal is transmitting on both the RATssimultaneously, the uplink transmissions on the two RATs can create IMdistortion products that fall in the resource allocations for the PUCCH.In case of a dual-RAT terminal where both the RATs are in active statesimultaneously, typically the service supported over one RAT is ofhigher priority than the service supported over the other RAT. Forexample, a voice session may be supported over one RAT and the other RATsupport a non-voice session. In such cases it is useful to be able tocontrol the communications for the data session such that the voicesession is given preference. This could lead to non-voice packets beingdropped occasionally and voice session being given preference instead.

In other cases, it might be desirable to convey UCI over one RAT that issupporting a data session and reduce the codec rate of the voice sessionsuch that both RAT transmissions can be simultaneously supported whilestill controlling the effect of IM distortion products created due tothe simultaneous transmissions. Thus, depending on the situation, itmight be useful to give preference to control information over userdata, or to give preference to high priority traffic such as voicetraffic over lower priority traffic such as non-voice (e.g., filetransfer, e-mail, etc.).

In FIG. 2, at 236, the controller includes UCI transmit controlfunctionality according to this embodiment by implementing instructionsstored in memory or using equivalent circuitry. In one embodiment, theUCI is transmitted on the PUSCH only when an allocation for the PUSCHfor the UCI transmission does not overlap desense resource blocks on thefirst RAT. The implementation of the embodiment of FIG. 4 may beindependent of the embodiments of FIGS. 1 and 3. Thus in embodimentswhere the terminal does not modify maximum transmit power, thecontroller in FIG. 2 need not implement the functionality 234. In otherembodiments, however, the maximum transmit power modification and UCItransmit control aspects of the disclosure may be implemented by aparticular terminal.

According to a related aspect of the embodiment illustrated in FIG. 4,the wireless communication terminal transmits an indication that thefirst RAT and the second RAT are concurrently active. Such atransmission may be made to a base station serving the terminal on thefirst or second RAT. In one implementation, the indication includes abit field indicating that the first RAT and the second RAT areconcurrently active. The base station on receiving such an indicationcan schedule the terminal appropriately for example, it can schedule theterminal outside the desense RBs.

In FIG. 5, according to another aspect of the disclosure, a multimodewireless communication terminal that communicates using a first radioaccess technology (RAT) and a second RAT determines, at 510, whether anassigned second RAT resource and any resource allocation on the firstRAT creates unacceptable inter-modulation (IM) distortion products onphysical uplink control channel (PUCCH) resource frequency locations ofthe first RAT when the first RAT is in an active state during a voicetransmission on the second RAT. In FIG. 2, the controller determines, at238, IM distortion products acceptability functionality according tothis embodiment by implementing instructions stored in memory or usingequivalent circuitry. In one embodiment. The acceptability orunacceptability of the IM distortion products may be determined bycomparison of the distortion products to a threshold.

In FIG. 5, at 520, the terminal discontinues transmission on the firstRAT while continuing the voice transmission on the second RAT upondetermining that the assigned second RAT resource and any resourceallocation on the first RAT creates unacceptable IM distortion productson the PUCCH resource frequency locations of first RAT. In FIG. 2, thecontroller performs RAT control 240 functionality according to thisembodiment by implementing instructions stored in memory or usingequivalent circuitry.

In FIG. 6, according to another aspect of the disclosure, a multimodewireless communication terminal that communicates using a first radioaccess technology (RAT) and a second RAT determines, at 610, determininga state of a first RAT of the terminal and more particularly whether thefirst RAT is in an active state. At 620, the terminal transmits to anetwork entity supporting the second RAT an indication of the state ofthe first RAT using a predefined value of a previously defined message.The message indicates to the network supporting the second RAT that theterminal is active on the other RAT. For example, a CDMA 1x/LTEmultimode terminal would indicate to the LTE network, on which the LTERAT of the terminal is conducting a non-voice session, that the terminalis also conducting a voice call or session on the CDMA 1x RAT. In someembodiments, transmitting the indication includes sending the previouslydefined message multiple times in a common uplink transmission sub-frameto indicate the state of the first RAT. At 630, the terminal adjusts amaximum transmit power limit of the first RAT or the second RAT based onthe predefined value of the previously defined message.

According to another embodiment, the UCI information is sent on PUSCH toavoid desense of PUCCH RBs when both the first and second RAT aretransmitting. Normally UCI is sent on the PUCCH. In FIG. 7, according tothis aspect of the disclosure, a multimode wireless communicationterminal that communicates using a first radio access technology (RAT)and a second RAT determines, at 710, determining whether the first RATand the second RAT are in an active state. In the multimode terminal ofFIG. 2, the controller is configured to perform RAT state determinationfunctionality 232 by implementing instructions stored in a memory deviceor by equivalent hardware circuits.

In FIG. 7, at 720, when both the first RAT and the second RAT are in theactive state and the second RAT is conducting a voice call in the activestate, then not transmitting uplink control information (UCI) over thefirst RAT in the absence of a scheduled PUSCH transmission. Thusaccording to this embodiment, the terminal drops or discontinues UCItransmission on sub-frame n if no corresponding scheduling PUSCH grantis received on an earlier sub-frame, e.g., sub-frame n-4. According tothis embodiment, a PUSCH must be scheduled before the UCI is transmittedover the PUSCH when the first RAT and the second RAT are activesimultaneously. In some implementations, the UCI is transmitted on thescheduled PUSCH transmission only when the PUSCH resource allocation forthe UCI transmission does not overlap desense RBs on a PUCCH.

In some network implementations, the wireless communication terminaltransmits an indication to a network supporting the first RAT that boththe first RAT and the second RAT are active. For example, in a CDMA1x/LTE multimode terminal, the terminal would send such an indication tothe network infrastructure entity supporting the LTE RAT. The indicationwould explain to the LTE network why UCI information has not been sent.

While the present disclosure and the best modes thereof have beendescribed in a manner establishing possession and enabling those ofordinary skill to make and use the same, it will be understood andappreciated that there are equivalents to the exemplary embodimentsdisclosed herein and that modifications and variations may be madethereto without departing from the scope and spirit of the inventions,which are to be limited not by the exemplary embodiments but by theappended claims.

1. A method in a multimode wireless communication terminal thatcommunicates using a first radio access technology (RAT) and a secondRAT, the method comprising: determining whether the first RAT and thesecond RAT are in an active state; modifying a maximum transmit powerlimit of the first RAT based on a voice codec rate of a voicetransmission on the second RAT when the first RAT and the second RAT arein the active state concurrently, wherein the second RAT is conductingthe voice transmission in the active state.
 2. The method of claim 1further comprising transmitting at a transmit power level on the firstRAT based on the modified maximum transmit power limit when the voicetransmission is conducted by the second RAT.
 3. The method of claim 1,wherein modifying the maximum transmit power limit of the first RATbased on the voice codec rate of the second RAT includes increasing themaximum transmit power limit of the first RAT when the second RATconducts the voice transmission using a relatively low voice codec datarate and decreasing the maximum transmit power limit of the first RATwhen the second RAT conducts the voice transmission using a relativelyhigh voice codec data rate.
 4. The method of claim 1 further comprisingmodifying a maximum transmit power limit of the second RAT whenmodifying the maximum transmit power limit of the first RAT.
 5. Themethod of claim 1, wherein modifying the maximum transmit power limit ofthe first RAT based on the voice codec rate of the voice transmissionincludes changing the maximum transmit power limit of the first RATduring a silence period of the voice transmission relative to anon-silence period of the voice transmission.
 6. The method of claim 5,wherein the maximum transmit power limit of the first RAT is increasedduring the silence period of the voice transmission.
 7. The method ofclaim 5 further comprising reducing a maximum transmit power limit ofthe second RAT during the silence period of the voice transmission.
 8. Amethod in a multimode wireless communication terminal that communicatesusing a first radio access technology (RAT) and a second RAT, the methodcomprising: determining whether the first RAT and the second RAT are inan active state; modifying a maximum transmit power limit of the firstRAT based on either a transmit power status of the second RAT or atransmission type of the first RAT when both the first RAT and thesecond RAT are concurrently in the active state.
 9. The method of claim8 further comprising transmitting at a transmit power level on the firstRAT based on the modified maximum transmit power limit when the firstRAT and the second RAT are in the active state concurrently.
 10. Themethod of claim 8 wherein modifying the maximum transmit power limit ofthe first RAT only occurs over a single slot of a subframe wherein onlythe single slot includes transmissions in frequency resources thatdesense the second RAT whereas another slot of the subframe does notinclude transmissions in frequency resources that desense the secondRAT.
 11. The method of claim 8, wherein the transmission type of thetransmission over the first RAT is either a control transmission or adata transmission.
 12. The method of claim 8, further comprisingincreasing the maximum transmit power limit of the first RAT when thetransmission type of the first RAT is a control transmission.
 13. Themethod of claim 8 further comprising increasing the maximum transmitpower limit of the first RAT and decreasing the maximum transmit powerlimit of the second RAT when the transmission type of the first RAT is acontrol transmission.
 14. The method of claim 8 further comprisingdecreasing the maximum transmit power limit of the first RAT andincreasing a maximum transmit power limit of the second RAT when thetransmission type of the first RAT is a data transmission.
 15. Themethod of claim 8, wherein the transmit power status of the second RATis selected from a group comprising: a transmit power headroom of thesecond RAT; a transmit power level of the second RAT; and a maximumtransmit power limit of the second RAT.